ABSTRACT

Wheat (Triticum aestivum L.), is a major cereal and staple food crop which plays the vital role in the economy of Pakistan. This wheat crop suffers a heavy toll in yield due to aphid attack, which affects plant vitality and grain production. Planting resistant/tolerant varieties against pests is the main way to overcome these field losses. Present study is an effort to screen different wheat varieties/lines against aphids under field conditions. Wheat varieties, Galaxy-13, Millat-11, Lasani-08, Faisalabad-08, and two wheat lines NW-1-8183-8 and NW-3-3341-7 were sown at Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad during the crop season 2015-2016. The aphid infestation started in mid-January on all wheat varieties at stem elongation stage and increased gradually with the growth of plants. Three aphid species were recorded i.e., Rhopalosiphum padi (L.), Schizaphis graminum (R.) and Sitobion avenae (F.). Mean seasonal aphid population (no. of aphids/tiller) on wheat plants during the whole season was the highest in NW-1-8183-8 and NW-3-3341-7 and the lowest in Faisalabad-08. However, grain yield was the highest in Galaxy-13 and the lowest was in Lasani-08 variety. Two applications of insecticide, (imidacloprid @ 625 ml/ hectare), significantly controlled the aphid population and enhanced the yield of all wheat varieties. The higher aphid infestations in untreated plots resulted in less chlorophyll content and reduced photosynthetic activity. Photosynthetic rate and chlorophyll contents were significantly higher in insecticide treated plots. Maximum cost-benefit ratio was found (1:9.2) in NW-1-8183-8 when treated against aphids. Wheat varieties, Galaxy-13 and Faisalabad-08 were found tolerant against aphid damage. Wheat variety Lasani-08 should be avoided because it was found susceptible to aphid infestations, and give low net yield. It is inferred that infestation of aphids significantly reduced the grain yield when not protected by insecticide. Insecticide protected crops give maximum net returns. Integration of varietal resistance and insecticides showed an effective reduction of aphids and gave a significant increase in grain yield.